This invention relates to medical-surgical instruments and a method of utilizing medical-surgical instruments for delivery of an anaesthetic drug. The invention is more particularly concerned with instruments and methods for use in the delivery of an anaesthetic for use as a nerve block.
A nerve block may be achieved through the administration of variable quantities of an anaesthetic agent to the plexus of a nerve. Since the nerve plexus is a very fragile structure, not capable of simple repair or reconstruction, it is crucial to do as little damage as possible in locating the point at which the plexus may be contacted.
It has been proposed to use a needle to locate the nerve in the usual way, and then to insert anaesthetic through the needle so that it emerges from the tip of the needle and contacts the nerve. An alternative procedure involves the proper positioning of the needle and the introduction of an epidural catheter through the needle. Once properly placed adjacent the nerve and into the plexus sheath of the patient, the epidural catheter may then be used to deliver variable amounts of anaesthetic for use as a nerve block.
It has also been proposed that an integral conductive wire be contained in the catheter, through which an electrical current may be applied to determine correct positioning of the catheter once it has been inserted through the needle. An electrical impulse sent through the conductive wire is utilized in determining proper placement of the tip of the catheter and, thus, the point at which the anaesthetic will be delivered.
Certain disadvantages exist with regard to the above referenced methods and the apparatus available to accomplish such methods. Most important among these is a danger associated with the uncertainty regarding the position of the needle tip. Such uncertainty could lead to nerve damage in manipulating the tip of the needle without knowing its position relative to nerves in the patient""s body. One reason for this uncertainty can be related to leakage of electricity. Placement of the catheter can have similar difficulties. In addition, the integral conductive wire in the catheter can be difficult to utilize effectively, as it is not rigidly attached to the remainder of the catheter apparatus. The catheter itself can also be unwieldy as it is usually of a very small diameter.
In accordance with the present invention, a catheter system is provided comprising: (a) a needle; (b) a catheter provided with an electrically conductive wire; and (c) a multipurpose connector provided with a structure able to make electrical contact with the conductive wire contained in the catheter.
The needle has a distal end and a proximal end. The distal end of the needle terminates in a beveled aperture having a sharp tip adapted for insertion into a nerve sheath of a patient so as to abut the nerve plexus. Contained in the needle and co-terminus therewith at the distal end is a removable stylet utilized in easing insertion of the needle into the patient. The proximal end of the needle is provided with a hub portion used for gripping the needle as well as for accessing the central bore of the needle. The needle, being of metal construction, is electrically conductive along its entire length. A non-conductive material may be used to coat the outer surface of the needle, leaving exposed portions of the proximal and distal ends of the needle, such that electrical voltage is not expended in unnecessary places.
The catheter is adapted for insertion through the hub portion and within and through the needle, with the distal end of the catheter capable of protruding out of the needle""s distal end. The catheter is formed primarily of a thermoplastic or related material which covers a tightly wound helical wire. The helical wire extends beyond the sheath material of the catheter at both the proximal and distal ends thereof. The helix formed by the wire leaves the center of the catheter structure available as a conduit. This central conduit of the catheter allows for administration of anaesthetic to the proximal end of the catheter.
The multipurpose connector allows the proximal end of the catheter to be inserted therein. Once inserted therein, the multipurpose connector may be manipulated to rigidly capture the proximal end of the catheter. The structure of the multipurpose connector allows the proximal end of the catheter to be accessed by a syringe or other apparatus for injecting fluid through the catheter. The multipurpose connector is also provided with electrical connections which electrically contact the helical wire of the catheter. These electrical contacts allow the helical wire of the catheter to be accessed despite the presence of the multipurpose connector over the distal end of the catheter and, thus, the protruding proximal end of the helical wire.
It is therefore an object of the present invention to provide a needle and catheter system including components, such that the position of an epidural needle may be identified by electrically stimulating and thus locating a specific nerve. When a specific nerve is located, the catheter is inserted through the needle to a point slightly beyond the distal tip of the needle. The catheter tip may then be manipulated and the optimum position for the catheter tip determined by applying an electrical voltage through the helical wire to the proximal tip of the helical wire, this electrical stimulation being utilized in locating the specific location of the catheter tip within the nerve. Once optimum placement is achieved, the catheter is utilized for continuous administration of anaesthetic.
Some of the objects of the invention having been stated above, other objects will become evident as the description proceeds below, when taken in connection with the accompanying drawings as best described below.